The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Vehicle electrical systems including electric machines, e.g., motors and accessory drive devices that receive electric power from energy storage devices, e.g., batteries, and are controlled by signals originating from control modules and other control devices and logic circuits. One electric circuit includes an electric-powered starter motor that spins an internal combustion engine when activated with an ignition switch. Control modules are electrically powered and functional to operate as intended only when electric power is greater than a minimum operating voltage for integrated circuits and other components thereof, e.g., 5V DC.
During an engine starting event, power draw by a starter motor can cause battery voltage and system voltage to fall below a minimum operating voltage of the integrated circuits of the control modules, thus affecting their ability to function. A known method for maintaining system voltage greater than a minimum operating voltage is to include a boost electric power supply in a control module, resulting in increased control module circuit complexity and associated cost.
In a hybrid vehicle system using an internal combustion engine in conjunction with electric torque machines to generate tractive torque, an auxiliary or accessory power module can be used in place of an alternator/generator to support low-voltage loads and electrically charge a low-voltage battery. The auxiliary power module converts energy from the high-voltage hybrid battery system to low-voltage to support the low-voltage system. A peak power rating for an auxiliary power module configured to provide electric power to a starter motor must be sufficient to operate the starter motor across a wide range of ambient conditions, engine operating conditions and associated electric loads. An auxiliary power module having sufficient electric power capacity to operate a starter motor may not be cost-effective.